1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device. In particular, the present invention relates to a method for forming an opening in thin films such as a conductive layer and an insulating layer.
2. Description of the Related Art
In a conventional technique, thin films such as an insulating layer and a conductive layer are formed over a substrate and a desired pattern is formed by a lithography technique, as appropriate, so as to manufacture a MOS transistor, a thin film transistor (hereinafter also referred to as a TFT), and a semiconductor device including such a transistor. A lithography technique is a technique in which a pattern of a circuit or the like referred to as a photomask, which is formed with a light-shielding material over a transparent flat plate, is transferred to an aimed object by utilizing light. The lithography technique has been widely used in a process of manufacturing a semiconductor integrated circuit and the like.
In the manufacturing process using a lithography technique, multiple steps such as resist application using a photosensitive resin referred to as a photoresist, pattern light exposure, development, etching using a resist as a mask, and resist removal are necessary. Therefore, the cost is increased and the throughput is decreased as the number of lithography steps is increased.
For example, a manufacturing method of a semiconductor device is described in Patent Document 1: Japanese Published Patent Application No. 2001-77194, in which lithography steps are simplified by removing the necessity of an etching step in forming an opening in an insulating film. Specifically, a resist film is formed in advance in a region where it is desired to form an opening, an insulating film is formed in a region other than the resist film, and the resist film is removed, whereby the opening is formed in the insulating film.